Fruit vegetables mainly include melons, solanes and beans. Every year in the northern part of the country, the protection of autumn and spring and the winter in the south (including protected areas and open fields) are serious. At present, it has become one of the most important diseases of fruit vegetables in China. First, the onset of symptoms symptoms, usually from the weaker cotyledons and the edge of the true leaf, the leaves become soft and drooping, the disease department was flooded at the beginning, after gradually turned light brown to brown, mostly semi-circular, disease department Often with a ripple pattern. When the conditions are right, the disease spreads along the petiole to the stem. After the initial flooding, the stem rots and thins, a large number of gray mold layers are born, and the plant folds in later stages. Sometimes the disease department develops faster in the longitudinal direction, causing serious injuries to one side and tripping. When the diseased plants and the healthy plants contact each other, the germs will spread to neighboring healthy plants, causing serious rot of the seedlings. In the adult stage, it can damage various parts of the ground. When leaves are damaged, they usually start from the tip of the leaf and the leaf margin, and are initially immersed in water. After the color is faded, they appear pale brown. The expansion of the lesion is generally not limited by the veins, and a shallow round is often formed on the tomato at the beginning of the disease. Patterned diamond or semicircular lesions on the leaves of vegetables such as kidney beans and eggplant, the lesions are nearly round, with camouflage, and are easily broken. When the damp spots, light gray sparse moldy layers are formed on the lesions. In wet conditions, the lesions continue to expand and even the whole leaves die. In the adult stage, the bacteria will spread to the stems and vines, causing them to sag and rot. This type of lesions often cause the stems to die. After the amphibian, the plants can be broken and the upper part dead. The legumes of leguminous vegetables are damaged, because they have a faster lignification and generally do not cause the breakage of the stems, but only the epidermis rots. When it is dry, the outer husks are cracked and fibrous. Although the damage to the stem of vegetables is mostly caused by the spread of pathogenic bacteria on the diseased leaf, it can also be directly infested, first forming a small spot and then expanding to the surrounding area. Such a disease spot is mostly in the delivery place. In addition, gray mold can also be invaded by wounds, broken stems and petioles caused by pruning, causing more serious losses. When the flower is damaged, it usually occurs from the early flowering period. Petals and bracts become soft, atrophic and rotten, and the surface is mildewed. In serious cases, the entire flower dies and spreads to other flowers, causing the flowers of the whole ear to die. In the fruit period, germs mainly enter the fruit through the declining petals or stigmas. When the fruit is onset, it can cause local whitening of the fruit surface, resulting in the emergence of thick gray mold and subsequent rot of the flesh. Sometimes the gray mold can invade directly from the fruit surface, forming some very fine ring spots on the fruit surface of the tomato, called "Psychosis". This spot does not generally have a significant effect on the yield. Second, the occurrence of the law of Botrytis cinerea mainly in the sickness of mycelium, sclerotia and conidia over the summer, with the help of air, rain, or dew spread. In addition, some agricultural operations, such as pruning, watering, flowering, or even walking in the fields, can be carried by people and spread. The expansion of Botrytis cinerea in the field is gradual. After the seedlings are infested, they mainly damage the leaves before they become buds. They enter the flowering stage and cause damage to the flowers. After the results, they damage the fruits. After the fruits are harvested, the disease will continue to spread on the leaves and vines if they are not pulled. Even if the diseased fruit, diseased leaf, or diseased plant that is taken off is not destroyed in time, the gray mold fungus will develop on it and become the initial infestation source for the next growing season. The germination of Botrytis spores requires certain nutrients. Therefore, the general infection of bacteria begins with the site where the host died or weakened. For example, the old leaves in the lower part of the plant, the tips of the leaves, the tendrils, the petal of the opening, the powdered stigma, etc. In addition, some of the larger wounds can also become the infestation points of the botrytis cinerea. The study on the pathogenicity of Botrytis cinerea in fruit and vegetable vegetables showed that the main infection site of the pathogen is in the fruit pedicle and its adjacent fruit surface and fruit umbilicus. The pathogens of the two infected sites were derived from the unsuccessful petal and the stigma after pollination. Therefore, the florescence of fruit vegetables and the weather conditions during fruit set have a greater impact on the disease epidemic. If we encounter continuous cloudy days at the flowering stage (ie, conditions of low temperature and high humidity), there will be more fruits that are affected near the fruit pedicel; if the fruit begins to grow and it is cloudy, the umbilical part of the fruit will be affected. many. The prevalence of Botrytis cinerea in fruit vegetables is related to the use of somatotropin. After the auxin is used, the petals of the fruit are often caught by the sepals and cannot be detached after the fruit enlarges, so that the germs have a foothold. The prevalence of gray mold in vegetables is also closely related to environmental conditions. The starting temperature of its mycelium development is 2°C, the highest is 31°C, and the optimum is 20-23°C. Some people think that in the solar greenhouse, indoor relative humidity can fully meet the requirements of the disease, and indoor temperature is the limiting factor of the disease epidemic. When the temperature below 15°C occurs for a long time, the occurrence of gray mold is heavy. Third, prevention and control methods According to the characteristics of the occurrence of such diseases, prevention and control should adopt comprehensive prevention and control measures based on chemical control. 1. Improvement and control of cultivation conditions (1) Soil treatment Since Botrytis cinerea in the fruit and vegetable vegetables is mainly in the soil as sclerotia, the protected land can be treated with soil disinfection. Among various methods, it is most economical to use solar heating materials. The specific approach is: after the spring vegetables in the protected area have been pulled (Beijing is in about the beginning of June), the diseased plants in the field will be treated cleanly, 500-1000 kg of plant ash will be applied every 667 m2, and 100 kg of slaked lime will be added. Turn it into the soil, make it into a bowl, pour enough water, cover it with a plastic film, and tightly cover the plastic film of the place of protection. Treat it 10-15 days. The protected ground in this way can have a ground temperature of 52°C in the depth of 2.20 pm on a sunny day. As long as there is such a temperature of 2-3d, the botrytis can be killed in the soil. (2) Removal of diseased and aging leaves, tendrils, and unsuccessful petals are the end-results of Botrytis cinerea in order to remove the disease in a timely manner. Therefore, in the prevention and control of Botrytis cinerea, in addition to the inspection at the seedling stage, the diseased leaves should be removed in time, and the fallen petals and stigmas should be removed when the fruit begins to expand. After melons, pumpkins, and melons are pollinated, it is also a very effective preventive measure to remove the flowers when the petals are wilting. After the onset of the disease, fruit should be removed in time with the fruit. When cleared, the diseased fruit can be put in a plastic bag and then picked up, concentrated and buried or destroyed. Don't throw it and throw it away without treatment, so as to prevent germs from multiplying on the diseased fruit. After the harvest, the diseased plants should be promptly removed, carried out outdoors and buried or destroyed. (3) Scientifically conducting field management 1 The density of planting should be appropriate: dense plants not only cause poor plant growth, but also cause premature senescence of the lower leaves, and the humidity of the field's microclimate is conducive to the occurrence of diseases. Strains should be increased in areas where gray mold often occurs. 2 Protection of fruits and vegetables to reasonably regulate the temperature and humidity of the environment: In the growing period of vegetables, consider the physiological requirements of vegetables at different times of the day. Such as cucumber, at 7 o'clock in the morning should be warmed up, so that the temperature inside the shed quickly rose to 28-35 °C, the afternoon gradually release the wind to prevent the disease prevention and control. 3 should pay attention to control the amount of nitrogen fertilizer to avoid excessive growth of plants, too tender. 4 After the onset of disease, proper water control should be conducted to avoid water accumulation in the field. Watering in protected areas should be carried out as early as possible in the morning on sunny days. After irrigation, the temperature should be raised after closing the shed to release water vapor. In addition, watering by spraying must be avoided to prevent the spores of Botrytis cinerea from being transmitted by water. 2. Chemical control and control of the resistance of pathogens There are many types of agents that can be used for prevention and treatment. When using, pay attention to choose the appropriate pesticide (1) protective agent chlorothalonil, captan, and thiram are effective against botrytis cinerea. Such fungicides have a broad spectrum of bactericides. It is convenient to use such agents when several diseases occur at the same time, and such bactericides are not easy to produce drug resistance, and the effect of control is relatively stable. However, it must be used before the onset or early onset, evenly sprayed, and used multiple times. (2) Obligate fungicides include: carbendazim, thiophanate-methyl, benomyl, tetrox, quick-acting, prohexine, nongrill, and Shijiale. However, Botrytis cinerea is more resistant to such fungicides. Generally, after a single and continuous use of 3-5 years, the effect is significantly reduced. (3) Compound fungicides Most commonly used in compound preparations are methoxaline, Lide, and Baoguoning No.2. The latter is a combination of auxin and fungicides mixed agents can only be used in spray flowers, can play a dual role in promoting fruit and disease prevention. (4) Agricultural antibiotics such as Wuyimycin and polyoxorubicin belong to such fungicides and are mainly used in some non-pollution vegetable fields. (5) Special bactericides for protected areas These fungicides mainly include various smoke agents and dusts. The species used can be selected based on the type of disease occurring and the level of local resistance to grey mold. If gray mold is still light in the protected area and other diseases are heavy, choose chlorothalonil-containing smoke or dust. If the local gray mold produces resistance to carbendazim or sulfasalm, then methadone, lidocaine, or powdered tobacco should be used. (6) The application of the "local two-phase defense" and "one-for-two" theory is mainly due to the invasive use of floral devices for vegetable and vegetable botrytis. Therefore, it is very effective to use the "local two-phase prevention" method for prevention and control. The so-called "local" refers to the application of the drug to the main infestation sites: petals, stigmas; the so-called "second phase" is to use a single drug in the flowering and fruiting stages, with emphasis on protecting the petals and stigma. Currently on the market, "Pangguoning No. 2" will mix bactericides used for disease prevention with auxin and work twice at a time with good results. However, it must be sprayed on the petals and on the stigma and not on pedicels and young larvae. In the case of gray mold on vegetables exposed to open fields, due to the wind in the fields, wettable powders or suspensions and water-soluble powder sprays may be used. Prevention of botrytis cinerea, but also to prevent germs against the anti-bacterial agent resistance. The "one-for-two" application technology developed by the Plant Protection and Environmental Protection Institute of the Beijing Academy of Agriculture and Forestry Sciences can delay or prevent the emergence of drug-resistant strains of Botrytis cinerea. The so-called “one change†is to replace the agent that has failed due to the resistance of the bacteria, and use a more effective agent. If the bacteria is resistant to quick-acting, use forexin and Shijiale. The so-called "second round" is to choose two types of different fungicides for rotation during the control. The rotation method is the use of different fungicides during flowering and fruiting. For example, Prunus persicum No. 2 spray can be used at the flowering stage of each ear fruit, and the enlarged fruit can be sprayed with 50% Litto WP 800 times solution at fruiting stage. Due to the different composition of the two agents, the bacteria are not susceptible to drug resistance. The use of this control method should be carried out from the time of flowering of the first panicle, and the effect of remedy will be significantly reduced when the disease occurs in the field.
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